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OB First Trimester Ultrasound Protocol Reviewed By: Spencer Lake, MD Last Reviewed: November 2020 Contact: (866) 761-4200, Option 1 Special Note: 1st Trimester OB US in the ED & B-hCG orders Please attempt to confirm positive beta-hCG (at least urine) before doing a 1st trimester US. When a 1st trimester US order is received from the ED, ensure a beta-hCG has been ordered. If there is time pressure from the ED/schedule to complete the examination prior to a positive result, it can be done with a pending beta-hCG CINE clips should be labeled: -MIDLINE structures: “right to left” when longitudinal and “superior to inferior” or “fundus to cervix” when transverse -RIGHT/LEFT structures: “lateral to medial” when longitudinal and “superior to inferior” when transverse **each should be 1 sweep, NOT back and forth** Some terms used: MSD = mean sac diameter FP = fetal pole CRL = crown-rump length FHR = fetal heart rate IUP = gestational sac + yolk sac (+/- embryo) IMPORTANT NOTE regarding 1 st trimester US: AVOID Doppler (color, spectral, power) when possible WHY limitations on Doppler in the 1 st trimester? -There is a potential risk of harm to a developing embryo from the increased heat associated with Doppler ultrasound (especially spectral and power) WHEN to use Doppler (this is detailed further below), very brief summary:

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Page 1: OB First Trimester Ultrasound Protocol

OB First Trimester Ultrasound Protocol

Reviewed By: Spencer Lake, MD Last Reviewed: November 2020 Contact: (866) 761-4200, Option 1 Special Note: 1st Trimester OB US in the ED & B-hCG orders

Please attempt to confirm positive beta-hCG (at least urine) before doing a 1st trimester US. When a 1st trimester US order is received from the ED, ensure a beta-hCG has been ordered. If there is time pressure from the ED/schedule to complete the examination prior to a positive result, it can be done with a pending beta-hCG CINE clips should be labeled:

-MIDLINE structures: “right to left” when longitudinal and “superior to inferior” or “fundus to cervix” when

transverse

-RIGHT/LEFT structures: “lateral to medial” when longitudinal and “superior to inferior” when transverse

**each should be 1 sweep, NOT back and forth**

Some terms used:

MSD = mean sac diameter FP = fetal pole CRL = crown-rump length FHR = fetal heart rate IUP = gestational sac + yolk sac (+/- embryo)

IMPORTANT NOTE regarding 1st trimester US: AVOID Doppler (color, spectral, power) when possible

WHY limitations on Doppler in the 1st trimester?

-There is a potential risk of harm to a developing embryo from the increased heat associated with

Doppler ultrasound (especially spectral and power)

WHEN to use Doppler (this is detailed further below), very brief summary:

Page 2: OB First Trimester Ultrasound Protocol

REQUIRED:

OVARIES/ADNEXA:

ED patient, all: color; spectral only certain indication/appearance (i.e., torsion)

Outpatient rule out torsion: color + spectral (document both venous and arterial flow)

Abnormal ovaries/adnexa - any adnexal mass or ovarian mass not clearly corpus luteum: color; spectral only for certain

indication/appearance

ENDOMETRIUM:

ONLY if abnormal endometrial findings without IUP or potential for IUP (i.e., gestational trophoblastic disease, retained

products of conception): color; if present, add spectral

OPTIONAL:

Suspected fetal demise (no HR) + CRL > = 7mm

TECHNIQUE: TA & TV vs. TA or TV only

ED patient: TA + TV for all* unless contraindicated or patient declines

*Note: proceeding to transvaginal imaging will be necessary in the majority of cases for optimal visualization and accurate measurements. If the sonographer believes that the transabdominal images are optimal and that transvaginal imaging is not needed, clearance must be given by the radiologist prior to release of the patient.

OUTPATIENT based on CRL dating: 1. CRL < = 8.6 weeks: TA+ TV* or TV only (if so ordered)

*Note: proceeding to transvaginal imaging will be necessary in the majority of cases for optimal visualization and accurate measurements. If the sonographer believes that the transabdominal images are optimal and that transvaginal imaging is not needed, clearance must be given by the radiologist prior to release of the patient.

2. CRL 9 – 11 weeks: Start with TA

Add TV: 1. If there is a >= 5 day discrepancy between LMP and CRL 2. If patient or physician is uncertain of LMP

**TA only will be OK if good views and < 5 day discrepancy between LMP and CRL**

3. CRL = > 11.1 weeks: TA only OK if good views and measurements adequate, even if >= 5 day

discrepancy between LMP and CRL or unknown LMP Can add TV if this would improve accuracy (technologist discretion)

Page 3: OB First Trimester Ultrasound Protocol

IUP or POSSIBLE IUP: GENERAL

Endometrial Contents: Gestational sac, yolk sac, fetal pole

Summary of CINEs through uterus REQUIRED on all 1st trimester examination, further detailed below:

(1) Overview of gestational sac/uterus: Single sweep (longitudinal or transverse) through uterus (best TA or

TV) to demonstrate gestational sac morphology and position

(2) Fetal Cardiac activity: short clip demonstrating presence of cardiac motion

GESTATIONAL SAC

-Presence, location, appearance and number of gestational sac(s)

-If there are multiple gestations, document amnionicity and chorionicity

-Sac to be measured (MSD) when:

(1) No FP or FP uncertain

(2) CRL < 12 weeks

NOTE: At 11.1 to 12 weeks, MSD can be omitted if it is difficult to obtain

-Document and measure subchorionic hemorrhage(s), if present;

Comment on location in relation to gestational sac

→ Comment if bleed encompasses < or >= 50% of gestational sac

-Comment on location of developing placenta, if it is seen (should be seen by 10 weeks)

-May say “too early to visualize” if it is not well seen (depending on gestational age)

Page 4: OB First Trimester Ultrasound Protocol

YOLK SAC

-Document and measure yolk sac

-Report if no yolk sac is seen, if yolk sac is enlarged, or if yolk sac is misshapen or otherwise abnormal

FETAL POLE

-Document and measure embryo/fetus

BRIEF SUMMARY:

LMP/dates <= 13w6d CRL

o If CRL >=84mm add biometry (and provide separate AUA)

LMP/dates >=14w0d biometry

o If Biometry <=13w6d add CRL (and provide separate AUA)

FURTHER DETAILS:

-At LMP/provided dating <= 13 weeks 6 days: measure CRL

Embryo should be magnified and in neutral position

-Use average of 3 discrete measures if all adequate, otherwise choose best

Provide AUA based on CRL

BUT IF CRL >= 84 mm, ADD biometry (BPD + HC + AC + FL)

Biometry: at least 2 measurements of each

-Use average if all adequate, otherwise choose best

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Provide 2 separate AUA: Do NOT average CRL and Biometry

(1) AUA for CRL

(2) AUA for Biometry

-At LMP/provided dating >= 14 weeks 0 days = 2nd trimester US: do biometry as per 2nd/3rd trimester US protocol

Biometry: at least 2 measurements of each

-Use average if all adequate, otherwise choose best

Provide AUA based on biometry

BUT IF Biometry <= 13 weeks 6 days, ADD CRL

Provide 2 separate AUA: Do NOT average CRL and Biometry

(1) AUA for CRL

(2) AUA for Biometry

-Cardiac activity, both M-mode and CINE for all:

(1) M-mode image(s): at least 1

→If fetal HR <120, >160 bpm, provide at least 2 M-mode tracings to confirm persistence

On worksheet, document both HR measures and average

(2) CINE video clip of beating heart/flutter

-Anatomy, if visible: Document bladder, stomach, extremities

-CRL >= 11 weeks: Add magnified midline true sagittal image of the fetus in neutral position

DOPPLER on the endometrium (color, spectral, power): most examinations should NOT have

Doppler on the endometrium (or its contents), more specifically:

NO DOPPLER for definite IUP or potential for IUP, including the following:

-No sac and otherwise normal endometrium

Page 6: OB First Trimester Ultrasound Protocol

-Possible gestational sac (empty or otherwise)

-Well-formed gestational sac (empty or otherwise)

SPECIAL NOTES:

(1) REQUIRED USE OF DOPPLER

Retained products of conception, gestational trophoblastic disease, and other endometrial

mass/abnormality without definite IUP or potential for IUP (as above) – TV imaging:

-CINE greyscale longitudinal and transverse, even if no abnormality identified at time of

examination

-Assess for color if endometrium is abnormal

If color present:

(1) Add spectral

(2) CINE color (best plane)

(2) OPTIONAL USE OF DOPPLER

CRL > = 7mm + NO heartbeat: per technologist discretion to better demonstrate lack of blood flow

(i.e., demise)

NOTE: if CRL < 7 mm + no FHR, do NOT use Doppler

Comments about early pregnancy dating and data to provide: 1. No FP or FP uncertain: MSD measured and associated date documented

**Estimated US gestational age based on MSD – this is just an estimate, CRL will be used for dating when embryo visible

2. + FP & LMP/dates <= 13w6d CRL

o If CRL >=84mm add biometry (and provide separate AUA)

o Provide MSD & associated dates if CRL <12w, but MSD not used for dating

3. + FP & LMP/dates >=14w0d biometry o If Biometry <=13w6d add CRL (and provide separate AUA)

Page 7: OB First Trimester Ultrasound Protocol

Additional Notes:

-Use “provided dates” or “LMP” or “clinical dates” when possible for expected dating

-Technologists should NOT re-date pregnancy based on other ultrasound(s) unless this dating is being used clinically

-See end of document for ACOG recommendations on pregnancy re-dating based on US – i.e., when OB would use US dates

to formally re-date the pregnancy

Maternal Structures:

**Do not need to include kidneys unless there is specific indication in order**

Uterus (other than gestational sac, yolk sac, fetal pole):

Measurement of size:

-If there is a gestational sac + yolk sac + fetal pole, uterine dimensions and volume do not need to be

performed/recorded.

--> All must be present (if not, please measure, as below)

--> Checkbox on worksheet: "appropriate gravid enlargement" (if this is accurate)

-If 1 or multiple of above are not present (i.e., gestational sac + yolk sac without fetal pole; sac-like structure;

questionable fetal pole; empty endometrium, etc.), uterine dimensions and volume should be performed and

recorded.

--> When measuring:

→ Length in sagittal from fundus to lower uterine segment (include cervix)

→ AP in same sagittal view as length (perpendicular to length)

→ Width in transverse view

→ Provide volume measurement (mL)

→ NOTE, if there is nothing in the endometrium, measure endometrial thickness

Documentation of general appearance:

Page 8: OB First Trimester Ultrasound Protocol

-Standard sagittal & transverse views

-Document fibroids; measure largest fibroid and any that may be affecting the gestational sac/endometrial

canal

-Do not use Doppler (color, spectral, power) on fibroids

Ovaries and Adnexa:

SUMMARY of when to CINE:

REQUIRED:

(1) No IUP and + b-HCG (i.e., possible ectopic): CINE both adnexa even if no obvious mass is identified, as below

-This includes empty “gestational sac-like structure”

(2) Ovarian/adnexal mass: ectopic or otherwise, detailed below

NOT required: IUP + normal ovaries/adnexa (including typical corpus luteum)

-No need to CINE ovaries with typical corpus luteum cyst

General

-Document and measure each ovary, document corpus luteum (if visible)

-Complete documentation of the ovaries requires several still images through each ovary in two planes per

ACR requirements, even if normal in appearance

Obtain 3 images in longitudinal plane (latmed or medlat) and 3 images in transverse plane

(supinf or infsup)

-Document adnexal regions (even if ovaries are both seen, need at least STILL images of both adnexa)

-If there is no IUP and + b-HCG, CINE both adnexal regions (even if no obvious mass is seen)

-This includes empty gestational sac-like structure

-Document any other ovarian or adnexal mass/cyst

Page 9: OB First Trimester Ultrasound Protocol

-If mass is identified: provide CINE in multiple planes

-If the mass is near or not definitively separate from the ovary:

→CINE to show mass moving separately from ovary, HOW to:

TV: use probe to separate ovary from mass; if this is not helpful, use non-scanning

hand to push on the abdomen to attempt to separate the ovary from the mass

Comment:

-If mass + ovary move together, it may be ovarian - likely corpus luteum

-If mass and ovary move separately, it is unlikely ovarian - concerning for ectopic

DOPPLER on ovaries/adnexa in pregnancy:

ED patients, all indications:

-Ovaries and adnexa: color only for all patients

-Add spectral to document waveforms ONLY if:

1. Indication is “rule out torsion”

2. Appearance is worrisome for torsion

Outpatient:

-Normal ovaries and adnexa: no Doppler of any kind

-Abnormal ovaries/adnexa or lesion that is not clearly the corpus luteum: color only

-Add spectral to document waveforms ONLY if:

1. Indication is “rule out torsion”

2. Appearance is worrisome for torsion

Cul-de-Sac:

-Evaluate for fluid; if present, document amount and if simple or complex

Page 10: OB First Trimester Ultrasound Protocol

-ED patient or outpatient for “rule out ectopic” and no IUP: evaluate for fluid in Morrison’s pouch (even if no

pelvic fluid)

-ED patient or outpatient with > = moderate pelvic free fluid and no IUP: evaluate for fluid in Morrison’s pouch

When to notify the radiologist before letting patient go (ED, inpatient or outpatient):

(1) Suspected demise

(2) Evidence of ectopic: either adnexal mass OR complex free fluid

(3) Any other required items on the “Sonographer to Radiologist Communication of Ultrasound Findings”

document.

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First Trimester Ultrasound Flow Chart